U.S. Pat. No. 7,952,337 discloses a hybrid switching voltage regulator of boost and/or buck topology. The voltage regulator comprises two separate feedback control loops wherein a first loop is an entirely analog and fast control loop and a second loop is a digital and slower feedback loop. The digital control loop comprises a DCB circuit which includes A/D and D/A converters surrounding an intermediate digital control engine.
US 2011/127983 discloses a system and method for controlling a digital pulse-width modulated power converter and achieves fast large-signal transient response while maintaining a slow response near the steady-state operating point in order to assure stability. Digital output error samples are processed through a gain scheduling block that applies a non-linear gain function to produce a weak loop response when the system is near its steady-state equilibrium point and a strong loop response when large transients are encountered.
Switched mode voltage regulator circuits are generally accepted as highly efficient power converter topologies for a diverse range of applications for example DC-DC voltage conversion or DC-AC voltage conversion etc. The regulator output voltage must generally be configured to track a predefined DC or AC reference voltage with high accuracy. A regulation loop is provided for the latter purpose and electrical characteristics of the regulation loop determine how accurate the reference voltage can be tracked. One type of switched mode voltage regulator circuits comprises regulation loops of PI type providing Proportional and Integral control. The speed at which the voltage regulator circuit is able to responding to load changes at the regulator output voltage is largely determined by how fast an integrator portion of the regulation loop can pull the regulator output voltage back to the set-point voltage indicated by predefined reference voltage. Therefore, a high or large integrator gain of the integrator portion of the regulation loop is advantageous.
Unfortunately, a high integrator gain tends to make the voltage regulator unstable in accordance with conditions determined by traditional feedback control theory. Consequently, it would be desirable to provide a voltage regulator with higher integrator gain than prior art voltage regulators to improve response time to load fluctuations and tracking accuracy of the regulator output voltage. It would also be advantageous to provide a PI regulation loop with high loop gain without stability problems and comprising digital processing of a digital error signal. It would furthermore be advantageous to minimize the amount of analog and/or digital circuitry of the regulation loop to reduce complexity, size and costs of the switched mode voltage regulator.